title: CCL20 Secretion from the Nucleus Pulposus Improves the Recruitment of CCR6-Expressing Th17 Cells to Degenerated IVD Tissues.
abstract: Studies elucidated that Th17 cells are important contributors to the pathogenesis of many immune-mediated diseases, and IL-17A is present in pathologic intervertebral disc (IVD) tissues. However, the mechanisms, how these cells traffic into the degenerate discs are not clear.
  
  
  
  The samples collected from 53 patients had been divided into 3 groups: Group P (annulus fibrosus was intact), Group E (annulus fibrosus was reptured) and normal control. Immunohistochemistry was used to detect the expression of CCL20, CCR6, IL-17A, TNF-α and CD4 in IVD tissues. Moreover, nucleus pulposus (NP) cells had been cultured in the presence and absence of Th17 associated cytokines. The supernatants were detected for CCL20 concentrations by ELISA, and the NP cells for the expression of CCL20 mRNA. Additionally, peripheral blood (PB) samples had undergone detection for the expression of CCR6 mRNA and the proportion of IL-17-producing cells, including the surface expression of CCR6.
  
  
  
  Immunohistochemistry revealed that CCL20 and TNF-α were expressed in degenerated NP cells. Double-labeled immunofluorescence elaborated, IL-17-producing cells (CD4(+)IL-17A(+) and CD4(+)CCR6(+)) appeared in the Group E samples, but no traces or expression in Group P and normal control. IL-17A and TNF-α, alone or combined, could enhance CCL20 secretion in a dose-dependent manner, which was obtained through RT-PCR results. There was a notable difference of CCR6 mRNA expression between patients and normal controls. In comparison to controls, flow cytometry data indicated that the proportion of IL-17-producing cells and the CCR6 expression in PB were significantly increased.
  
  
  
  Our results provide a potential explanation for involvement of the CCL20-CCR6 system in the trafficking of IL-17-producing cells to degenerated IVD tissues. Additionally, our results explain the contribution of Th17 associated cytokines to the development of degenerated discs via the up-regulation of CCL20 secretion from NP cells, which forms a positive chemotactic feedback loop.
authors.affiliation: Department of Orthopedics, Qilu Hospital, Shandong University, Jinan, Shandong, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Zhang
authors.forename: Lin
authors.initials: L
authors.lastname: Nie
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Xu-Ping
authors.initials: XP
authors.lastname: Wang
authors.forename: Hua
authors.initials: H
authors.lastname: Zhao
authors.forename: Samina
authors.initials: S
authors.lastname: Dongol
authors.forename: Sailendra
authors.initials: S
authors.lastname: Maharjan
authors.forename: Lei
authors.initials: L
authors.lastname: Cheng
mesh_terms: D000293:Adolescent; D000328:Adult; D054418:Chemokine CCL20 / Q000235:genetics / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D020381:Interleukin-17 / Q000378:metabolism; D007403:Intervertebral Disc / Q000378:metabolism*; D055959:Intervertebral Disc Degeneration / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D000070614:Nucleus Pulposus / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D054399:Receptors, CCR6 / Q000378:metabolism*; D058504:Th17 Cells / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D055815:Young Adult
chemical_list: C108355:CCL20 protein, human; C106311:CCR6 protein, human; D054418:Chemokine CCL20; C508717:IL17A protein, human; D020381:Interleukin-17; D012333:RNA, Messenger; D054399:Receptors, CCR6; D014409:Tumor Necrosis Factor-alpha